Researchers at the University of Tokyo Science are developing new electrochemical technologies to produce ammonia-based fertilizers from urea.
From the perspective of the future society, in a closed environment such as a space station, self-sufficiency in food management and waste management is very important. However, the technology to achieve this is still lacking. In a new study, scientists from Japan explain the latest breakthrough: a cheap and efficient way to make liquid artificial fertilizer (ammonia) from simplified artificial urine, serving the ideal double purpose for growing food and treating waste.
In extreme environments, even the most ordinary job can seem like an insurmountable challenge. Because of such difficulties, mankind, for the most part, settled on better reasons for harvesting, herding livestock, and building shelters. But as we seek to extend the limits of human exploration, both on earth and in outer space, those who pioneer this search will surely face situations that, for all intents and purposes, are not conducive to human habitation.
One of the most important challenges to face is the long-term intended settlement, either in Antarctica or beyond Mars (thought in the near future), towards achieving some level of autonomy, so that isolated colonies can survive despite severe failures in provision. And the key to achieving this autonomy is to ensure adequate feeding and independence. Not surprisingly, therefore, space agricultural technology is one of the research topics currently being conducted by the Research Center for the Space Colony at the University of Tokyo Science. Researchers here hope to lead the development of technology for safe space agriculture with the aim of supporting humans for a long time in a closed environment such as a space station.
To this end, an innovative study conducted by a team of Japanese researchers led by Associate Professor Norihiro Suzuki of Tokyo University of Science — this study, published as a “Letter,” makes for a prestigious front cover Journal of New Chemistry of the Royal Society of Chemistry. In this study, Dr. Suzuki and his team aim to discuss food production issues in enclosed environments, such as those in space stations.
Realizing that farmers have been using animal waste as fertilizer for thousands of years, as a rich source of nitrogen, Dr. Suzuki and his team have studied the possibility of making urea (a major component of urine), to produce liquid fertilizers. It will also simultaneously discuss the problem of human waste treatment or space management! As Dr. Suzuki explains, “This process is favored by the point of view of making a useful product, namely ammonia, from waste products, namely urine, using general equipment at atmospheric pressure and room temperature.”
The research team also includes Akihiro Okazaki, Kai Takagi, and Izumi Serizawa from ORC Manufacturing Co. Ltd., Japan devised an “electrochemical” process to extract ammonium ions (usually found in standard fertilizers) from artificial urine samples. Simple experimental preparation: on the one hand, there is a “reaction” cell, with a “boron-doped diamond” (BDD) electrode and a non-soluble catalyst or “photocatalyst” material that cannot be created from titanium dioxide. On the other hand, there are “counter” cells and simple platinum electrodes. As current is passed to the reaction cell, the urea oxidizes, forming ammonium ions. Dr. Suzuki described this breakthrough as follows, “I joined ‘Space Agriteam’ which is involved in food production, and specializes in physical chemistry; so, I came up with the idea for ‘electrochemistry’ to make liquid fertilizers.”
The research team then investigated whether cells would be more efficient in the presence of photocatalysts, by comparing cell reactions with and without them. They found that during the initial decay of urea more or less the same, nitrogen-based ions were produced differently both at the time and distribution when the photocatalyst was introduced. In particular, the concentrations of nitrite and nitrate ions are poor in the presence of photocatalysts. This suggests that the presence of photocatalysts promotes the formation of ammonium ions.
Dr. Suzuki stated, “We plan to experiment with native urine samples, as they contain not only the primary elements (phosphorus, nitrogen, potassium) but also the secondary elements (sulfur, calcium, magnesium) that are essential for plant nutrition!” Thus, Dr. Suzuki and his team are optimistic that this method provides a strong basis for the production of liquid fertilizer in a confined space, and, as such. Dr. Suzuki observed, “It would turn out to be useful for long-term protection in enclosed spaces such as space stations.”
Humans who inhabit Mars may be a distant reality, but this research certainly seems to indicate that we can be on the path to ensuring sustainability — in space — even before we really get there!
References: “Formation of ammonium ions by urea electrochemical oxidation with boron diamond electrodes” by Norihiro Suzuki, Akihiro Okazaki, Kai Takagi, Izumi Serizawa, Genji Okada, Chiaki Terashima, Ken-ichi Katsumata, Takeshi Kondo, Makoto Yuasa and Akira Fujishima, 16 Sé 2020, Journal of New Chemistry,
DOI: 10.1039 / D0NJ03347B